Single letter feeding device



June 13, 1961 J. RABINOW ETAL 2,988,355

SINGLE LETTER FEEDING DEVICE Filed May 4, 1959 2 Sheets-Sheet 1 T0 /3 7'0 /2 F/G/ T0 /9 Q 26 r Ill i 5 f REJECT SIGNAL WVE/VTORS F t Lg, L/ACOB RAB/Now Q24 HAROLD J ROSENBERG JOHN G M MACDONALD ATTORNEY June 13, 1961 J. RABINOW ETAL 2,988,355

SINGLE LETTER FEEDING DEVICE Filed May 4, 1959 2 Sheets-Sheet 2 g} a) K5 T HAROLD J ROSENBERG J .27 22% g JOHN G M Mncoo/v/ua Br Xm ATTORNEY United States Patent O 2,988,355 SINGLE LETTER FEEDING DEVICE Jacob Rabinow, Takoma Park, and Harold J. Rosenberg,

Silver Spring, Md., and John G. M. MacDonald, Washington, D.C., assignors, by direct and mesne assignments, of eighty-five percent to said Rabinow, and fifteen percent to Max L. Libman, Vienna, Va.

Filed May 4, 1959, Ser. No. 810,941 r 8 Claims. (Cl. 271 -2) This invention relates to the art of feeding mail or similar items in the form of cards, sheets or envelopes, one at a time, from a stack into a utilization machine which may be a coding device or a letter sorter.

One of the basic mechanisms required in all handling of mail is a feeding device that can feed one letter at a time. Many systems have been built in the past. Two

basic types are (1) where the letters are fed byfriction parallel to their own surface, that is, the letters are shaved off ei-ther from the bottom or from the top of a stack, or 011 the side, if the stack is lying on its side, or, (2) where a vacuum cup picks up one letter at a time and drops it into the subsequent operation. A major difiiculty of all such machines is that because of the various sizes, thicknesses, and weights and variable nature of the envelopes, it is very difficult to make sure that only one letter at a time is picked up. In the present trend towards auto matic post oflices, the feeding of doubles is getting to be a more important problem. For example, in the case of a stamp cancelling machine, if two letters are fed at a time, one. stamp may not be cancelled. This causes no particular hardship, particularly because the lack of cancelling marks will be noticed by human operators who subsequently sort the letter and, in any case, someone can cancel the letter manually. In any case, the lack of cancellation causes no great hardship on the Post Ofiice or the user of the mail. In the case of automatic sorting machinery, however, the feeding of a double can be quite serious because if one of the two letters should be ad- -dressed locally while the other letter is addressed to a ing the uncertainty of friction between various pieces of mail.

It is, therefore, a major object of this invention to provide an improved vacuum feed system which provides very great safety against doubles, that is, which has very little chance of feeding more than one letter at a time.

Another object is to provide a double-cup vacuum pickup system for transferring letters from one vacuum cup to another to minimize doubles, especially doubles due to different sized letters, and to porous letters.

A further object is to provide a novel means for separating doubles by subjecting opposite sides of a selected piece of mail to lateral friction-a1 forces in different directions to separate any possible doubles, and to provide means for testing for such separation.

Another object is to also test the picked-up letters for true individuality and to provide means for rejecting doubles.

A practical embodiment of the invention, shown in more detail below, employs a horizontal feeding table to present the front piece of a stack of mail to a vacuum cup.

A photocell is used to sense the front of the stack and control the feed table so that the front pieces of mail are loose, i.e. under no pressure than their own weight. An edging belt is provided to move the front pieces of mail Patented June 13, 1961 edgewise against a reference Wall. A first vacuum cup picks mail off the stack and presents it to a second vacuum cup which transfers it one at a time to the subsequent operation.

The specific nature of the invention, as well as other objects and advantages thereof, will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings, in which:

FIG. 1 is a schematic perspective view showing the general arrangement of our machine;

FIG. 2 is a schematic side view of the machine better shows the path of the vacuum cups;

FIG. 3 is a view similar to FIG. 2, but showing an alternative arrangement of vacuum cups; and

FIG. 4 is a top elevation of the doubles testing and rejection chute, showing the control circuit therefor.

The letters are presumed to have been faced, that is, oriented with all the addresses one way, before they reach our machine, although this is of no particular importance to the invention. The letters are placed so that they "lie at about a 45 angle to the vertical, as shown, and rest on moving belts 1. The 45 angle was chosen because when a more vertical position is used, the entire stack is 'aifected by the weight of the front letter, and when a heavy letter is removed from the front, tends, like a long spring, to tip the front of the stack over the end of the table. The belts 1 are driven by a motor 2a controlled by a photocell 2. A light source 3 is mounted on the opposite side of the table and the light from this source is interrupted by the letters as they move forward. When the light is interrupted, the motor stops and the letters rest in this position until the light path is again free. As the circuit and mechanical means for accomplishing this action are conventional per se, they are not shown in detail.

It should be noted that the surface supporting the stack of letters runs down a slight ramp 4a, just at the point where the stack of letters is stopped, so that the foremost three or four letters tend to slip down the ramp to a more nearly horizontal position. This tends to spread out and separate the letters, so that the front letter tends to slide individually off the ramp 4a.

As the letters move into their pickoif position at the end of the ramp 4a, they reach a point Where a second belt 5 moves at right angles to the table as shown in FIG. 1. This belt is made of rubber or other suitable plastic material and is normally shaped like an L so that the front letter resting in the corner of the trough 6 rests against this belt as shown in FIG. 2. As this belt passes over the pulleys, it flattens out. The L-shaped belt is supported in its working position by the front wall of the trough. The function of this belt is to move the letters sideways against the reference wall 7 so as to control their horizontal location.

A first vacuum cup, indicated by numeral 8, is supported by pipe fittings including one which allows it to rotate about the axis of shaft 9. Similarly, a second vacuum cup 10 is mounted for rotation about the axis of shaft 11. The air pressure in these cups is controlled by valves 12 and 13, respectively. Valves 12 and 13 are conventional three-way valves, which can connect the vacuum cups either to a vacuum supply manifold or to atmospheric pressure.

Vacuum cups 8 and 10 are oscillated synchronously about axes 9 and 11 by a suitable mechanism shown schemati-cally as a slow-speed motor 30 driving a crank arm 31 so that each revolution of the motor causes a substantially oscillation of the shaft 9. Motor 30 also drives a stack of rotary switches 32 connected to the respective controlled units 12, '13 and 19, and havingtheir stationary contacts adjusted to produce the desired timing relationship. The motor thus drives shafts9 and 11 so which the smallest letter which it is expected to handle. letter which was incorrectly edged will fall into receptacle the space between closely stacked cards. such cards are in close contact with each other, the front the force with whichone is held.

that the vacuum cups meet in the position shown in phantom in FIG. 2 and so that cup 8 is in position to pick up a letter off the stack when cup 10 is in position to drop a letter into the channel 17.

Valve -12 is timed to supply vacuum to cup 8 when it is in position to pick up a piece of mail from the stack on table 4 and while the cup moves to the transfer position where it meets cup 10 face-to-face. When the cups are in this transfer position, valve 12 connects cup 8 to atmospheric pressure and valve 13 connects cup 10 to vacuum, and these valve positions are maintained on the return stroke so that cup 10 holds the piece of mail until it is in a position to drop it into channel 17 and cup 8 is back to a position adjacent the stack of mail. Any suitable timing switch mechanism may be employed for this purpose.

According to a preferred embodiment, the two vacuum cups move in phase with each other according to an approximation of simple harmonic motion and valve timing is substantially as described above. However, cup motions could be slightly out of phase; the motion could be, for instance, cycloidal or a step function; and the valve timing could be modified without departing from the spirit of the invention.

Because of the various sizes of the letters, which may vary-from three by four inches in their dimensions to six by twelve, the vacuum cup has to be located close to wall 7 and close to the surface of the table, approximately in the position shown by phantom line rectangle in FIG. 1. As human operators place the letters on the table, the edging of the letters is not usually perfect, that is, not all the letters are pressed firmly against the back surface 7. Some small letters may be invisible in the stack and they may find themselves in the position of the small letter on the front of the stack, shown in FIG. 1. This is the major cause of doubles. Consider, for example, what happens when the two envelopes arrive at the vacuum station. The friction edging belt does not always have enough time tomove the front letter against the edging surface 7. Sometimes the letters do not slide down on each other because of the interaction of flaps, or high friction between them, and the front letter never reaches the edging belt 5 at all. Under these conditions, the vacuum cup will come in at the position shown by the phantom line rectangle and pick up both letters. There have been cases where three letters are picked up at one time in a similar fashion. Consider again the case of the simple double. The two letters are turned over so that the opposite surface is presented to the second vacuum cup as was presented to the first vacuum cup. It will be noted that in most cases the last letter to be picked up by cup 8 will 'be substantially properly edged against wall 7 and the belt 5 and this last letter will be the only one presented to cup 10, since cup 10, as well as cup 8, is smaller than The 14 where it will remain until manually re-stacked on table 4. If three letters are picked up, the action will be the same except that now two letters will fall into the re- 'As is well-known to those in the art of mail handling with vacuum, some light-weight single-thickness pieces of mail such as post cards are very porous and a vacuum cup will very often pick up two cards simply because there is enough air flow through the first card to evacuate When two one in contact'with'the vacuum and atmospheric presdivides across them and the back one is held with half If this force is greater than'the weight of the card, two are picked off like one 'andoften transferred to the second vacuum cup as one.

To help overcome this difliculty, we have provideda mechanical force which adds to the weight of such cards tending to separate them and allow air to get between them. One means of providing such force is indicated in FIG. 1 by the concave shape of vacuum cup 8 which bends post cards. Any shape of vacuum cup which distorts the normally flat shape of a post card will serve this purpose. Cups, so distorted, must still be able to handle heavy stiif pieces of mail. Therefore, we have made cup entirely of soft rubber-like material in the shape shown in FIG. 1, and we have also made rigid cups with thin rubber flaps along the distorted edge, not shown, which also serve the same purpose.

Another device which helps separate cards is shown in FIG. 3 wherein similar parts are similarly numbered. In this embodiment, the vacuum cups do not meet faceto-face but act on offset areas, so that if the vacuum is maintained in cup 8 while the two cups begin to separate, instead of the cards being balanced between equal vacuums, there is some atmospheric pressure opposite at least a portion of each cup to hold both cards to both cups. The outside card, in each case, however, in the case of porous cards discussed above, is held with only half the force with which the inside one is held. The vacuum needs to be maintained in cup 8 only until the cards are deflected enough to separate in the area adjacent cup 10, then air maybe admitted to cup 8 and the second card of the double dropped into receptacle 14. To aid in this separation, one of the cups may be pivotally mounted and spring biased for limited rotation out of parallel with the other cup, about an axis close to its front surface. FIG. 3 shows cup 10 so mounted. The cup is swivelly mounted on its arm and held in the position shown by spring 10a. In this design, when the cups are in their transfer position, they overlap slightly to overcome the spring bias of 10a on cup 10 and bring the cup surfaces into parallel to make sure that cup 10 comes into close contact with the piece of mail to be trans ferred.

Channel 17 is part of a conveyor which moves the letters horizontally through the channel such as from lower-right to upper-left in FIG. 1. Due to the wide variety of physical properties of mail, the above-described machine may still deliver some doubles to channel 17. We, therefore, provide a doubles detector in channel .17 comprising two rubber rimmed friction wheels 15 on opposite sides of channel 17, mounted for movement toward each other through slots in channel 17. Wheels 15 are spinning in such direction that if brought together on opposite sides of a double, they will tend to move the two pieces of mail in opposite directions along channel 17 so as to cover the two holes 16. Under the same conditions, a single piece of mail may go in either direction and cover either hole 16, but not both. The photocells are mounted to detect light through holes 16 and wired to produce a signal when both holes are covered. Said signal is used by machines or operators to take appropriate action, as described below.

Wheels 15 are driven by constantly-rotating motors 18 in opposite directions. Normally, the wheels are out of contact, but each time a piece of mail is dropped by pickup 10 into channel 17, a contact on the switch timer which controls the operations above described is momentarily closed to energize a solenoid 19 which through a linkage 21 acts to momentarily bring the two friction wheels 15 toward each other and into contact with the letter. If it is a single, it will be shunted to either side and cover only one hole 16, and thus fail to energize the circuit to be described below; in this case, since the wheels 15 separate almost immediately, moving belt 21 carries the letter onto its destination. If there .is a double, then one letter is shunted in one direction and the other inthe other direction by the Wheels 15, and both holes 16 are covered. This actuates both relays 22 and 23 which are connected to the respectivephotoeell circuits, and causes relay 24 to operate, which closes the reject circuit 26; this actuates solenoid 27 which causes gate 28 to assume the dotted line position for an instant and shunts out the two letters into a reject container so that they are not delivered. The rejected letters are then re-sorted by hand or re=stacked and put on belts 1 for sorting.

Instead of rejecting both letters, the timing can be arranged if desired to reject one letter and pass the other.

It will be apparent that the embodiments shown are only exemplary and that various modifications can be inade in construction and arrangement within the scope of our invention as defined in the appended claims.

We claim:

1. A feeding and separating device for feeding and separately delivering separate ones of a stack of sheets of semi-stiff, flexible sheets such as pieces of mail, comprising movable horizontal conveyor surface means, means for supporting said stack on said last means with the individual sheets thereof loosely leaning back at an angle, conveyor stop means for stopping the forward motion of said conveyor means when the foremost letter of the stack has reached a predetetermined position, first vacuum cup pick-up means, means for moving said pick-up means alternately between a first position in which it engages said foremost letter to pick it off the stack, and a second position in which it releases the letter; second vacuum cup means alternately movable between a third position opposite said second position in which it picks up said letter from said first vacuum cup and a fourth position in which it drops said letter on edge into a delivery chute, edge conveyor means at the bottom of said chute for conveying said letter to a delivery point; doubles separating means having two oppositely rotatable friction wheels, means for momentarily moving said wheels into contact with opposite sides of said letter to separate any doubles; means associated with said chute for detecting said doubles after separation, and reject means for rejecting such detected doubles.

2. A letter feeding device comprising a moving support for moving a stack of letters in a generally horizontal direction toward a delivery point, moving vacuum cup means to pick up a load comprising the front letter of said stack or the front two letters constituting a double, when the two letters are so displaced that the vacuum cup means can contact both letters, at said delivery point and move said load to a predetermined location laterally away from the rest of the stack in such orientation that when the load is a double, one letter of such double is above the other, a second vacuum cup means movable to said location to engage the said picked off load from the upper side while it is held by the first cup, vacuum control means to turn off the vacuum of the first cup and turn on the vacuum of the second cup so as to cause the letter which it picks up to be transferred at said location, motion control means to move said second cup with its attached letter to a second location laterally displaced from said first location, whereby the bottom letter of a double will remain near said first location, and vacuum control means to shut off the vacuum of said second cup at said second location to release said letter.

3. The invention according to claim 2, the engaging surface of said vacuum cups being flexible and curved to distort an engaged letter out of its normally flat shape.

4. A letter feeding device comprising a moving support for moving a stack of letters in a direction generally along the axis of a stack, moving vacuum cup means to pick up the front letter of said stack and move it to a predetermined location away from the rest of the stack,

a second vacuum cup means movable to said location to engage the said picked off letter from the opposite side while it is held by the first cup, vacuum control means to turn off the vacuum of the first cup and turn on the vacuum of the second cup so as to cause the letter to be transferred at said location, motion control means to move said second cup with its attached letter to a second location, and vacuum control means to shut off the vacuum of said second cup at said second location to release said letter, and a narrow letter chute at said second location for receiving a letter from said second cup on edge, oppositely rotating friction wheels on opposite sides of said chute, and means for moving said wheels simultaneously into frictional engagement with opposite sides of said letter in said chute to separate any doubles by moving the components of such doubles in opposite directions in said chute.

5. The invention according to claim 4, and two photoelectric detecting stations spaced along said chute on opposite sides of said friction wheels by a distance greater than the length of one letter and less than the length of two letters for detecting such doubles, and letter reject means operated by simultaneous signals from said detecting stations.

6. A letter feeding table comprising a horizontally moving conveyor surface for supporting the bottom edges of a stack of letters with the individual letters thereof loosely leaning back at an angle, and moving same toward a letter pickoff end, and edging means at the end of said table comprising a vertical side reference surface so located that at least one edge of each letter is put into a cominon plane by abutting said surface, said edging means comprising also a moving friction belt transverse to said moving conveyor at the end thereof, upon which the bottom edge of at least the front letter of the stack rests when it reaches said pickup end, with the bottom edge of the letter in contact with the surface of said belt, said belt moving toward said reference surface to frictionally urge the letter against said reference surface.

7. The invention according to claim 6, said belt being of sufficient width to simultaneously accommodate several letters.

8. A letter feeding table comprising a horizontally moving conveyor surface for supporting on edge a stack of letters and moving same toward a letter pickoif end, and edging means at the end of said table comprising a vertical side reference so located that at least one edge of each letter is put into a common plane, said edging means comprising a moving friction belt transverse to said moving conveyor, upon which at least the front letter of the stack rests when it reaches said pickup end, with the bottom edge of the letter in contact. with the surface of said belt, said belt moving toward said reference surface of frictionally urge the letter against said reference surface, said belt being flexible, and means for turning up the belt edge which is nearest the pickoii end so that the belt surface forms an angle to prevent the foremost letter from moving forwardly off the belt.

References Cited in the file of this patent UNITED STATES PATENTS 783,206 Juengst Feb. 21, 1905 1,585,368 Blaine May 18, 1926 2,294,273 Buxbaum Aug. 25, 1942 2,926,910 Martin Mar. 1, 1956 2,761,680 Lens Sept. 4, 1956 2,764,408 Weiler Sept. 25, 1956 2,792,218 Van Marle May 14, 1957 2,853,296 Skow Sept. 23, 1958 

